Nonscoring brake adjuster



Sept; 12, 1950 F. KRlKoRlAN NoNsooRING BRAKE ADJUSTER 2 sneek-sheet 1 Filed oct; 25, 194e Sme/Mem 7A a n Sept. l2, 1950 4 F. KRIKQRIAN 2,522,181

- NoNscoRING BRAKE ADJUSTE'R Filed oct. 25, 194e 2 sheets-sheet 2 ze f7-4? Patented Sept. 12, 1950 UNIT E D vSTAT ES PATENT OF FICE y NUNSGORINGBRAKE ADJUSTER Frank Krikorian, Lowell; Mass;

Application October 23, 1946, Serial No. 705,046

rlihis invention relatesto improvements in brake adjusting devices, and more particularly to a brakeadjuster for automatically adjusting the brake clearance during theuse of the brakes.

It is an object of this invention to provide a brake adjuster of the kind torbe more specically described hereinafter which comprises a pawl andl ratchet between the brake operating mechanism and the brake shoe for maintaining the clearance between the brake lining and the brake drum between certain predetermined limits.

Another object or this invention is to` provide a brake adjusterof lthis kind which is -so con-y structedfv and arranged that the brake clearance will be held between certain speciedi limits de= spite thewear on thebr'ake lining, and which is providedA with a spring-pressed stop varrangement for stopping' the adjusting mechanism' when the bra-ke lining is completely worn out, thuspreventing the scoring of, the brake drums by the rivets which hold `the lining to the shoes.

Still another objectV oi' this inventioni's to prom vide a brake adjuster ofthis kind which may be readily adjusted for use on any type of automobile or truck whether"using'hydraulic or mechanical brakes. y

A further object-of this invention is to provide an improved brake adjuster which is constructed Figure 7 isl an enlarged fragmentary section of the braise adjuster of Figure 6, the lock being shown in locking position.

Referring to the drawings, the numeral II] designates generally a brake adjuster constructed according tc an embodiment of my invention. This brake adjuster IQ is adapted to be fixed on a bra-ke between the braise shoe I I and the brake shoe operating means I2.

The brake adjuster It consists of a housing or sleeve i4 which is fixed relative to the brake. They housing or sleeve i4 may be formed at one end with an annular recess I for slidably` engagn ing over the end of a brake cylinder I6, the xed endl of the cylinder being removed, and is fixed thereon` by a set screw lI-'I engaging through the wall of the sleeve l@ and cylinder I6. The sleeve I is further formed with a deep recess |81 at the same end `as the recess i5 outwardly of thecylin-` with a minimum number of moving partswhile l" providinga highly eicient devicel of this'kind, thereby providing for a minimum of vmaintenance diiculties and a minimum `amount oflabor for repairing such maintenance problems as might h i inwardly and upwardly inclined teeth 22.

thebrake as an attachment or as a part of the original assembly.`

With the above and other objects in View, my invention consists in the arrangement, combination and details of" construction disclosed inthe drawings and specification, and then more`par-l ticularly pointed out in the appended claim.

Invthe drawings:

Figure 1 is a side elevationlof my brake adjuster on a brake assembly, the" brake drum and shoe beingfbroken away,

Figure 2 is a vertical longitudinal" section thereof, i

Figure 3 is a transversersection taken on the line 33\of Figure 2,

moved from the assembly,

Figure 5 is a vertical section taken ontheiline modified formof brake adjuster, and

der |15. A square opening I9 is formed in the center'of the sleeve Iii' longitudinally thereof andcommunicates at its inner end with the recess I8. Near the outer end of the housing It there is pro-s vided. a bore- 2i]Y at right angles to the axis of the cylinder I4 through one wall thereof which communicatesl with the opening I 9 from outside of the cylinder.

A` rectangular block 2| slidably engages in the opening I9 and is formed on its upper side with aseries of transverse rearwardly inclined serrations or notches 22 which form a ratchet having The block 21| alone is freely slidable in the opening I9 but' is limitedin its movement therein by a pawl 24 having downwardly and outwardly inclined teeth 25 engageable in the teeth or notches 22m block 241| whereby the block 2| may slide only outy wardlyl of thesleeve It: The pawl 2t is slidably housed in the opening' or bore 2t in the cylinderA I4; The. pal-W1241 is constantly urged into engage-a ment with the ratchet 2| by a spring 26 which engages about the upstanding lug 21 on the pawl 24 and bears against the upper side of the pawl 24f`. The upper endof the spring` 26 bears against the lower end of a plug screw 28 threadably engaged' inthe upper end of` the bore 2t.

Aeonnecting rod 29 extends througl'i` theblock 2|. and'is, slidable. therein inthe bore 30 through` blockli.` The rod. 2.9 is connected at its outer endlto the-free.. end, of the brake shoe II by a `pivotbolt 32. The inner, end of. the bolt 29 is provided! witha rounded cap. or bearing. surface llfwithinithefrecess I8 of thevhousing It and- Flgu're 4 is a top plan view of the ratchet rethe brake shoe |I out of engagement with the 3 brake drum 31. This spring 36 is in addition to the conventional spring 38 fixed at one end to the brake shoe II and at its other end to the brake itself.

The cap 34 is adapted to bear against the outer end of the piston 39 in the brake cylinder I2. A nut 40 on the outer end of the rod 29 is adapted to bear against the outer end of the block 2| to limit the inward movement of the rod 29.

In the use and operation of the brake adjuster I0, on installation the brake clearance 4| is determined from the manufacturer and set by moving the nut 40 on the rod 29until the clearance between the brake drum 31 and brake lining 42 is obtained. Then in the use of the brake, when the brake pedal in the machine is depressed, the piston 39 is caused to move outwardly. Movement of the piston 39 presses the rod 29 outwardly to engage the lining 42 with the drum 31. After initial movement of the rod 29 outwardly when the spring 36 is completely compressed and the brake is not yet set, further movement of the rod 29 causes the block 2| to slide outwardly with the rod 29 until the brake is set. Under normal conditions, the sliding of the block 2| is less than the length of one tooth 22 whereby when the brake pedal is released the rod 29 and block 2| are returned to their original position by springs 38 and 36. As the brake lining 42 wears and the clearance 4I nears the extreme limit, the movement, of the block 2| will reach the length of one of the teeth 22 and cause the block 2| to be held outwardly at the next tooth 22 so that the rod 29 when being returned to starting position will return a distance shorter by the length of the tooth 22 so that the clearance 42 is again brought to a minimum distance. The block 2| is continually stepped outwardly upon wearing of the lining 42 and is held against movement inwardly by the pawl 24 engaging the ratchet teeth 22. When the lining 42 is worn past safe limits, the lining may be replaced in a conventional manner and the brake adjuster reset by removing the screw plug 28 and allowing the block 2| to slide inwardly to the first clearance adjustment desired, which will be a minimum.

The spacing of each tooth 22 will be less than the difference between the maximum and minimum brake clearance so that the clearance will always be within safe limits.

With the use of the brake adjuster I as described above, the block 2| will be moved outwardly 'to take up the wear on the lining 42 irrespective of the thickness of the lining, and

when used as described above will keep adjusting l the brake clearance until the rivets which hold the brake lining on are rubbing the drum 31 which causes scoring thereof.

In order to prevent such scoring of the drums 31 and to stop the block 2| in its outward adjusting movement, there is provided a notch 44 on the lower side of the block 2| transversely thereof, and a pin 45 carried by the housing I4 is adapted to engage in the notch 44 and bore 48 in the housing I4. The pin 45 is slidably carried in the bore 46 in the housing I4, and normally engages the lower flat surface of the block 2|.v A U-shaped bracket 41 is xed to the housing I4 over the bore 46 and pin 45, the pin 45 being formed with a reduced diameter outer extending end 48, which extends through the bracket 41. A spring 49 about the reduced end 48 of the pin 45 within the bracket 41 pressespin 45 inwardly of the housing I4. In the initial lsetting and adjusting of the brake adjuster I0, the block 2| is pushed inwardly so that the notch 44 is a distance inwardly of the pin equal to the maximum total amount of wear permissible on the lining 42, so that as the lining 42 becomes .worn and the shoe II is adjusted to compensate for this wear, when the lining is worn to a point just before the rivets will score the brake drum 31, the pin 45 will engage in the notch 44 to prevent any further outward adjustment of the block 2| whereby the drums will be saved from scoring by the' rivets which hold the lining 42 on the brake shoe II.

When the lining 42 has become entirely worn and the pin 45 has engaged in the slot 44, this condition may be indicated to the operator of the vehicle by providing a switch 50 operated by the pin 45, so the operator will be warned to have the brakes relined at the earliest possible time. The switch 58 includes a xed contact 5| on the bracket 41, which may be connected by suitable wiring to the battery 52, and a moving contact 54 fixed in the pin 45, which is connected to a light bulb 55 on the dashboard of the Vehicle or other suitable alarm.

When the pin 45 is in its outer position as the adjuster I8 is in position for use as such, the switch 50 is open, and when the pin slides into the notch 44 the switch 50 is closed, as shown in Figure 7, completing the electrical circuit to the alarm or bulb 55.

I do not mean to confine myself to the exact details of construction herein disclosed, but claim all variations falling within the purview of the appended claim.

What I claim is:

A brake adjusting device of the kind described comprising a housing, a ratchet member slidable in said housing, a spring-pressed pawl engaging said ratchet member limiting the sliding thereof to one direction, a rod slidable in said ratchet member and operatively connected to a brake shoe, an abutment member on said rod engageable with one end of said ratchet member for sliding said ratchet member against said pawl, an operator for said brake shoe operatively connected to said rod, a lost motion connection including a compression spring between said rod and said ratchet member for sliding said member after initial movement of said rod upon complete compression of said spring, said ratchet member formed with a recess along the length thereof, a spring pressed locking pin carried by said housing engageable in said recess for locking said ratchet member after a determined sliding movement thereof in said housing, a fixed switch contact member on said housing, and a switch contact member on said locking pin engageable with said fixed contact for closing an electric alarm circuit when said pin engages in said recess.

FRANK KRIKORIAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

